1. Field of the Invention
The present invention relates to a thermoelectric device configured in a manner that heat-absorbing-side electrodes are attached onto heat-absorbing surfaces of a plurality of thermoelectric elements, heat-radiating-side electrodes are attached onto heat-radiating surfaces of the respective thermoelectric elements, and all of the thermoelectric elements are connected electrically in series and thermally in parallel. Particularly, the present invention relates to a thermoelectric device having good manufacturability and excellent joint reliability.
2. Description of the Related Art
A thermoelectric device is composed by combining thermoelectric elements utilizing thermoelectric effects such as the Thomson effect, the Peltier effect and the Seebeck effect, and has already been in high-volume production as a temperature regulation unit which converts electricity into heat. Moreover, also as a generator, researches and developments of the thermoelectric device have been progressed.
In a thermoelectric device as the generator, a plurality of thermoelectric elements are arrayed in a state of being sandwiched between insulating boards having electrodes, and are connected electrically in series and thermally in parallel.
In order to make power generation efficiency of the thermoelectric device approximate to power generation efficiency of the thermoelectric elements themselves, it is necessary that heat supply to one ends of the thermoelectric elements and heat radiation from the other ends of the thermoelectric elements be performed smoothly. For this reason, for the boards constituting the thermoelectric device, ceramic boards excellent in thermal conductivity are used. Furthermore, the electrodes arranged on the ends of the thermoelectric elements are composed of a material having low electric resistance.
The thermoelectric device operates by being heated, and during the operation, the respective constituent members are thermally expanded as compared with those at normal temperature. In this case, due to a difference in coefficient of linear expansion between the respective constituent members and a temperature difference between the heat-absorbing side and the heat-radiating side, deformation amounts of the respective members differ from one another. Because of such a difference in thermal deformation, in some cases, joint parts of the thermoelectric elements and the thermoelectric elements themselves have become prone to be damaged.